Screening method of thermo-sensitive genic male sterile line with hybrid seed production safety and breeding safety
By screening temperature-sensitive nuclear sterile rice at different altitudes, the temperature-sensitive nuclear sterile lines with pollen sterile at high temperatures and pollen fertile at low temperatures were screened, and the problem of hybrid seed production and reproduction failure caused by temperature-sensitive nuclear sterile lines at high temperatures or low temperatures was solved, and the safety of hybrid seed production and reproduction and high yield and stable yield were achieved.
Patent Information
- Application Number
- CN202510592369.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-09
- Publication Date
- 2025-08-05
AI Technical Summary
In the prior art, temperature-sensitive nuclear sterile lines are prone to failure of hybrid seed production and reproduction under high or low temperature conditions, resulting in safety and economic problems of two-line hybrid rice. Especially in the rice areas of the middle and lower reaches of the Yangtze River and Baoshan area of Yunnan, the frequency of high or low temperatures is high, affecting the reliability of seed production and reproduction.
By planting temperature-sensitive nuclear sterile rice at different altitudes (1450m, 1650m, 1750m and 1850m), the pollen fertility and fruiting rate were observed, and the temperature-sensitive nuclear sterile lines that were pollen sterile at high temperatures and pollen fertility at low temperatures were screened to ensure the safety of hybrid seed production and reproduction.
The selected temperature-sensitive nuclear sterile lines are pollen sterile at high temperatures and pollen fertility at low temperatures, achieving safety of hybrid seed production and high yield and stable yield of sterile lines, solving the problem of reproduction failure, and improving the safety and economicality of two-line hybrid rice.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of rice breeding, and in particular relates to a method for screening a thermosensitive nuclear male sterile line with safe hybrid seed production and reproduction. Background Art
[0002] Annong S-1 (1988) is the first thermosensitive nuclear male sterile material discovered in my country. Its characteristics are that its pollen is sterile under high temperature conditions, making it suitable for hybrid seed production as a sterile line; under low temperature conditions, its pollen is fertile and can be used to propagate sterile seed, a dual-purpose line. The method of producing hybrid rice using this sterile line is called the "two-line method" for hybrid rice. However, research has shown that the threshold temperature for high-temperature-induced pollen sterility in Annong S-1 is 25°C. That is, when the average daily temperature from the pollen mother cell to the meiotic stage is above 25°C, the pollen becomes sterile, and below 25°C, the pollen becomes fertile. Analysis of historical meteorological data indicates that short-term low temperatures with an average daily temperature of 25°C are frequent in the rice-growing areas of the middle and lower reaches of the Yangtze River during midsummer. This temperature-induced fertility in the sterile line leads to failure in hybrid seed production. The region's average temperature rarely falls below 23.5°C for six consecutive days during midsummer. Therefore, a six-day treatment at 23.5°C from the pollen mother cell to meiotic stage yields a pollen sterility rate of 99.9%, a standard used to select thermosensitive genic male sterile lines, thereby improving the safety of two-line hybrid seed production. However, as the sterility threshold temperature decreases, seed propagation of sterile lines, such as Zhu 1S and Tanzao S, becomes more difficult. Although some success has been achieved in breeding sterile lines at 1500-1650m in Baoshan, Yunnan, widespread failures in Baoshan occur annually. There are two main reasons for reproductive failure: First, at this altitude, the average daily temperature frequently rises above 23.5°C during midsummer, with daily maximums reaching 28-29°C. This results in the loss of harvest for sterile lines with low sterility thresholds, such as Zhu 1S and Tan Zao S (which have a sterility threshold of 22.5°C and are safe for hybrid seed production), due to high temperatures during their sensitive fertility periods. Even sterile lines with a sterility threshold of 23.5°C suffer yield reductions due to high temperatures. Second, at an altitude of 1650m, daily minimum temperatures frequently fall below 20°C. This causes physiological damage to cold-sensitive sterile lines, such as Zhu 1S, Tan Zao S, Zhu S, and Guangzhan 63S, resulting in pollen sterility and reproductive failure. Therefore, the dual safety of hybrid seed production and sterile line propagation has always been a core issue for two-line hybrid rice, a major contributor to the debt of many seed companies and a contributing factor to the high price of two-line hybrid rice seeds, which increases farmers' grain production costs. Therefore, the selection and breeding of "double-low" sterile lines that are safe in hybrid seed production (the sterility starting temperature is low, around 22.5°C) and reproductive safety (pollen development can withstand low temperatures of 16°C-19°C) has become an urgent need for the development of the two-line method industry. Summary of the Invention
[0003] In order to obtain a thermosensitive genic male sterile line with safe hybrid seed production and reproduction, the present invention provides the following technical solutions:
[0004] The present invention discloses a method for screening a thermosensitive genic male sterile line with safe hybrid seed production and reproduction, the screening method comprising the following steps:
[0005] (1) Planting thermosensitive genic male sterile rice in summer at altitudes of 1450 m, 1650 m, 1750 m, and 1850 m in Baoshan City, Yunnan Province, using conventional fertilizer and water management;
[0006] (2) Observe and record pollen fertility during the heading and flowering stages of thermosensitive genic male sterile rice;
[0007] (3) Calculate the seed setting rate and determine the theoretical yield per mu during the maturity period of thermosensitive genic male sterile rice;
[0008] (4) Calculate the average daily temperature 15-22 days before heading of the thermosensitive genic male sterile rice lines;
[0009] (5) Screening of thermosensitive nuclear male sterile lines for safe hybrid seed production and reproduction: Thermosensitive nuclear male sterile rice lines whose pollen is sterile when the average daily temperature is higher than 22.5℃ and whose pollen is fertile when the average daily temperature is lower than 20℃ are thermosensitive nuclear male sterile lines for safe hybrid seed production and reproduction.
[0010] Preferably, the thermosensitive genic male sterile rice line that is pollen sterile at 1450 m and pollen fertile at 1750 m and 1850 m in step (5) is a thermosensitive genic male sterile rice line that is safe for hybrid seed production and reproduction.
[0011] Preferably, in step (5), the fruit setting rate of the thermo-sensitive genic male sterile rice is above 70%.
[0012] Preferably, in step (5), the theoretical yield per mu of the thermo-sensitive genic male sterile rice is above 500 kg.
[0013] Beneficial effects of the present invention:
[0014] The applicant found through meteorological data analysis and planting experiments that the average temperature of festivals in midsummer at an altitude of 1850m in Baoshan, Yunnan Province is all lower than 22.5 ℃, and there is no condition for high temperature induction of sterility, but the low temperature frequency of 15 ℃ is very high, which is an ideal condition for screening the low temperature resistant sterile lines of pollen development, but because the plant tillers are few due to the low temperature, the plant height is on the short side, which is not conducive to high yield. Under the condition of 1750m, the average temperature of festivals in midsummer is all lower than 22.5 ℃, and there is no condition for high temperature induction of sterility, but the minimum temperature intensity is less, and the duration is shorter, and the sterile line plants grow luxuriantly, and the sterile line pollen of pollen development resistance to low temperature is fertile, and the fruit setting rate can reach more than 70%, and the yield per mu is more than 500kg, which can realize the high yield and stable production of sterile line. And the sterile line of pollen sterility at an altitude of 1450m can ensure the safety of seed production in the high-yield seed production area of the two-line method (south of 30 degrees north latitude, about 300m above sea level). BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 This is a diagram showing the fruiting results of the sterile line obtained by the screening method of the present invention at altitudes of 1450m and 1850m. DETAILED DESCRIPTION
[0016] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.
[0017] The present invention aims to provide a method for screening rice double low-temperature-sensitive genic male sterile lines and safe seed propagation using temperature differences at different altitudes. By utilizing the rice double low-temperature-sensitive genic male sterile lines, safe hybrid rice seed production and safe sterile line seed propagation in the two-line hybrid rice method can be achieved.
[0018] The method for screening rice double low-temperature-sensitive genic male sterile lines and safe seed propagation using temperature differences at different altitudes of the present invention comprises the following steps:
[0019] (1) A nursery field (99.19E, 25.30N) was prepared at an altitude of 1650 m in Baoshan City, Yunnan Province. Germinated sterile seeds were sown around April 15. Routine fertilizer and water management was carried out during the nursery period.
[0020] (2) Around May 15, the rice seedlings were transplanted to rice fields at altitudes of 1450 m, 1650 m, 1750 m, and 1850 m, with each sterile line planting group of about 300 plants (the area for the production of sterile lines is not limited). Conventional fertilizer and water management was implemented, and the temperature of the rice field during the growing period was recorded using an automatic temperature recorder.
[0021] (3) Observe and record pollen fertility during the heading and flowering stages;
[0022] (4) Calculate the fruit set rate and determine the theoretical yield per mu at maturity;
[0023] (5) Calculate the average daily temperature of the sterile line 15-22 days (7 days) before heading;
[0024] (6) The sterile lines with pollen sterile when the average daily temperature is higher than 22.5℃ and fertile when the average daily temperature is lower than 20℃ are called “double low” thermosensitive genic sterile lines; otherwise, they are called “double high” thermosensitive genic sterile lines (pollen fertile when the average daily temperature is higher than 22.5℃ and sterile when the average daily temperature is lower than 20℃), “high low” thermosensitive genic sterile lines (pollen fertile when the average daily temperature is higher than 22.5℃ and sterile when the average daily temperature is lower than 20℃), and “low high” thermosensitive genic sterile lines (pollen sterile when the average daily temperature is higher than 22.5℃ and sterile when the average daily temperature is lower than 20℃).
[0025] The specific operation is: pollen is fertile at an altitude of 1450m, but is sterile at an altitude of 1650m and above. This type of sterile line is a "double-high" temperature-sensitive nuclear sterile line, that is, the starting temperature for high temperature-induced pollen sterility is high, and the temperature for low temperature physiological damage to sterility is high (pollen development is not resistant to low temperature).
[0026] Pollen is fertile at 1450-1850m. This type of sterile line is a "high-low" thermosensitive genic sterile line, meaning that the starting temperature for high-temperature-induced pollen sterility is high, while the temperature for low-temperature physiological damage to sterility is low (pollen development is resistant to low temperatures).
[0027] Pollen sterility occurs at 1450m and at 1650m and above. This is a "low-high" thermosensitive genic male sterile line. This means that high temperatures induce pollen sterility at a low starting temperature, while low temperatures cause physiological sterility at a high temperature.
[0028] Pollen is sterile at 1450m, fertile at 1750m and 1850m, and the fruit set rate is over 70% at 1750m. This type of sterile line is a "double low" temperature-sensitive nuclear sterile line.
[0029] One such screening method yields a "double-low" thermosensitive genic male sterile rice line: When exposed to a daily average temperature above 22.5°C during the pollen fertility-sensitive period, pollen becomes sterile, enabling safe hybrid seed production. When exposed to a daily average temperature below 20°C during the pollen fertility-sensitive period, pollen becomes fertile, enabling safe breeding of sterile seeds at an altitude of 1,750 meters.
[0030] The present invention uses the temperature difference at different altitudes to screen the double low-temperature sensitive genic male sterile lines of rice. By comparing 365 temperature-sensitive genic male sterile lines, two double low sterile line materials were found, among which the "double low" sterile line did not bear fruit at an altitude of 1450m ( Figure 1 Left), strong at an altitude of 1850m ( Figure 1 right).
Claims
1. A method for screening thermosensitive genic male sterile lines with safe hybrid seed production and reproduction, characterized in that: The screening method comprises the following steps: (1) At different altitudes of 1450m, 1650m, 1750m and 1850m in Baoshan City, Yunnan Province, Planting thermosensitive genic male sterile rice in summer, wherein the thermosensitive genic male sterile rice is planted using conventional fertilizer and water management; (2) Observe and record pollen fertility during the heading and flowering stages of thermosensitive genic male sterile rice; (3) Calculate the seed setting rate and determine the theoretical yield per mu during the maturity period of thermosensitive genic male sterile rice; (4) Calculate the average daily temperature 15-22 days before heading of the thermosensitive genic male sterile rice lines; (5) Screening of thermosensitive nuclear male sterile lines for safe hybrid seed production and reproduction: Thermosensitive nuclear male sterile rice lines whose pollen is sterile when the average daily temperature is higher than 22.5℃ and whose pollen is fertile when the average daily temperature is lower than 20℃ are thermosensitive nuclear male sterile lines for safe hybrid seed production and reproduction.
2. The screening method according to claim 1, wherein The thermosensitive genic male sterile rice that is pollen-sterile at 1450 m and pollen-fertile at 1750 m and 1850 m in step (5) is a thermosensitive genic male sterile line with safe hybrid seed production and reproduction.
3. The screening method according to claim 1, wherein In step (5), the fruit setting rate of the thermo-sensitive genic male sterile rice is above 70%.
4. The screening method according to claim 1, wherein In step (5), the theoretical yield per mu of the thermo-sensitive genic male sterile rice is more than 500 kg.